You *most definitely* have CPUTYPE defined somewhere. There is no
default make.conf, and the example make.conf in /usr/share/examples/etc
does not define CPUTYPE=pentium anywhere.

The error is telling you that you should use CPUTYPE?=processor, not
CPUTYPE=processor.
> I've never set CPUTYPE in the past. I don't want specific CPU
> optimizations as I am building for multiple generations of processor.
>
> What is a person to do?

If you've tinkered with make.conf at all, you may have some quotation
madness going on there which is running amok. Regardless, this very
much looks like an issue specific to your system.